Adsorbing material for blood and plasma cleaning method and for albumin purification

ABSTRACT

The invention relates to an adsorbent material, a method for cleaning blood and plasma and purifying albumin, and to a method for producing said adsorbent material. The inventive adsorbent material is embodied in the form of a highly cross-linked and porous spherical divinylbenzene copolymer which contains from 4 to 30 weight % of an imidazole derivative and at least 50 weight % of divinylvenzene incorporated by radical polymerization in the presence of air and/or oxygen. Said adsorbent material is embodied in such a way that it is biocompatible and suitable for removing free and albumin-bound toxic substances, drugs, pharmaceutical products, endogenic and exogenic toxins from blood, plasma, and external albumin circuits at a high rate and efficiency. The material is used in particular for adsorbing bilirubin and bile acids and is produced by suspension polymerization.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicants claim priority under 35 U.S.C. § 119 of German ApplicationNo. 102 61 910.7 filed on Dec. 30, 2002. Applicants also claim priorityunder 35 U.S.C. § 365 of PCT/DE2003/004297 filed on Dec. 29, 2003. Theinternational application under PCT article 21(2) was not published inEnglish.

The present invention relates to an adsorbent material for methods ofblood, blood plasma, and albumin purification as well as a method forproducing said material.

Fields of application of this invention are special medical andpharmaceutical methods for the purification of blood, blood plasma, andalbumin, which remove free and albumin-bound toxins from blood, bloodplasma, and albumin. These methods are used to treat poisoning withpharmaceuticals and drugs, poisoning with chemicals and highly doseddrugs for chemotherapy, acute and chronic kidney failure, acute andchronic liver failure (e.g. hyperbilirubinemia, cholestasis, hepaticencephalopathy, fulminate liver failure), and multiple organ failure.

Conventional methods of blood purification are divided into membranetechniques (hemodialysis, plasmapheresis, ultrafiltration), adsorptiontechniques (hemoperfusion, plasmaperfusion), and combinedmembrane-adsorption techniques (e.g. MARS®).

Membrane techniques remove unwanted substances from a liquid mixture bybringing the mixture in contact with a rinsing solution trough a semipermeable membrane where the rinsing solution is free from the substanceto be removed (dialysis). The concentration difference of the unwantedsubstance between the mixture and the rinsing solution is the drivingforce for concentration equilibration. If the pore size of thesemipermeable membrane is such that the unwanted substance can passthrough it then concentration equilibration will occur by permeation ofthe unwanted substance into the rinsing solution. In hemolysis membranesare used whose pores are wide enough for the toxins to be removed and atthe same time small enough to retain blood components with biggermolecular dimensions such as albumin, hemoglobin, erythocytes,leukocytes, and thrombocytes.

In adsorption techniques (hemo perfusion, plasma perfusion), blood orblood plasma flows through a column or cartridge which is filled with amacroporous material such as activated charcoal, an adsorbent polymer,or ion exchanger, and is thereby detoxified. In plasma perfusion bloodcells have to be separated before the adsorption step and reunited withthe plasma after treatment.

The MARS method belongs to the combined techniques of extracorporealblood purification comprising a combination of dialysis and perfusion.In the MARS method, the patient's blood flows through an albumindialyser and then back to the patient. A pure albumin solution with aconcentration of 5 to 20% circulates on the wash side of the albumindialyser. Since most blood toxins are bound to albumin this creates thedriving force for the toxins to pass through the dialyser membrane.After passing the albumin dialyser the albumin solution is purified inan in-line perfusion block followed by a standard dialyser and thenreturned to the albumin dialyser. With this principle it is possible toreplace the detoxifying function of the liver which is life-threateningin liver failure.

Hemo dialysis, ultrafiltration and plasma pheresis separate bloodcompounds according to their size and mostly unselectively. In contrastto this, sorption techniques can work selectively as well as lessselectively. Membrane techniques require tailored membranes, andsorption techniques require tailored adsorbents.

For extracorporeal blood purification methods activated charcoal is usedas an adsorbent as well as increasingly synthetic, macroporous adsorbentpolymers. Disadvantages of charcoal are the driving force for thisdevelopment. These include low mechanical stability, low selectivity andlow adsorption speed, further high retention of white blood cells andblood platelets, and initiation of blood clots.

In the literature, the following polymer adsorbents are described:

-   -   1. porous and highly porous styrene-divinylbenzene copolymers,    -   2. macroporous divinylbenzene copolymers,    -   3. macroporous methacrylate and acrylate co- and terpolymers,        respectively,    -   4. porous, pearl-shaped cellulose derivatives.

SU 732207 describes sorbents produced from activated charcoal and coatedactivated charcoal, e.g. with a solution of poly(acrylic acid) orpoly(acrylic acid) and poly(ethylene amine). Further polymer coatings ofactivated charcoals are described in U.S. Pat No. 4,048,046, U.S. Pat.No. 4,171,283, U.S. Pat. No. 5,420,601, and SU 844569. However, thedisadvantages of activated charcoal such as low mechanical stability andlow adsorption speed could not be eliminated with these methods.

Macroporous styrene-divinylbenzene copolymers have been used to removebarbiturates and glucothimides from dog blood in 1974 according to U.S.Pat. No. 3,794,584. However, it has been shown later, that thesematerials are highly non-polar, non-selective, and incompatible withblood. Highly porous styrene-divinylbenzene copolymers with a specificsurface greater than 800 m²/g, obtained by post-crosslinking of weaklycross-linked styrene-divinylbenzene copolymers using monochloro dimethylether in the presence of Friedel-Crafts catalysts, were also described12 years later in 1986 as especially effective and fast-adsorbingmaterials for hemo perfusion in DD 249274A1. These adsorbents also showinsufficient blood compatibility and require additional post-treatment.Furthermore, their production is accompanied by high risks for humansand environment because of the use of carcinogenic monochloro dimethylether.

Special, complex modification of the surface of highly porousstyrene-divinylbenzene copolymers with trifluoralkoxyphosphazenes (U.S.Pat. No. 5,773,384) can improve blood compatibility. However, additionalmodification decreases the specific surface and pore accessibility aswell as enormously increases the purification efforts since allremaining reagents and catalysts must be removed from the macro, meso,and micropores of the polymer prior to use in hemo perfusion.

Surface modification of highly crosslinked divinylbenzene copolymers bycoating or grafting polymerization is described in recently filed patentapplications U.S. Pat. No. 6,419,830 (2001) and U.S. Pat. No. 6,423,024(2002) to produce highly porous, spherical divinylbenzene resins for theadsorption of health-threatening substances such as β-2-microglobulinefrom blood or plasma. The coating is performed on commerciallyavailable, highly porous divinylbenzene copolymers consisting of 60 to90% divinylbenzene, having a specific surface of 200 to 1600 m²/g, poresizes from 20 to 500 Å, total pore volume up to 2.5 ml/g and particlesizes from 25 to 2500 μm. The hemocompatible coatings are obtained byreaction of residue vinyl groups on the surface of the DVB copolymerwith hemocompatible monomers or polymers comprising phosphatidylcholine,heparin, polyalkylene glykolene, polyalkoxyphosphazenes, and poly(vinylpyrrolidone). Other coatings claimed consist of various vinylpyridine-,vinylimidazole-, and vinylpyrrolidone-derivatives as well as variousderivatives of acrylic acid and methacrylic acids. The obviousdisadvantage of these methods is that the hemocompatible coating isapplied subsequently, thereby leading to a reduction in specific surfaceand pore accessibility as described above. Further disadvantagescomprise the complete removal of the monomers used for the coating whichare often considered harmful or even carcinogenic. Therefore, thepurification of polymers modified using these methods to behemocompatible is complex, expensive and not quite risk-free.

On the other hand, coatings applied from polymer solutions often havethe disadvantage that they can be partially dissolved in aqueousisotonic solutions of sodium chloride or in body fluids and thus enterthe blood circuit of a patient in an uncontrolled way.

Thus, there is need for an essentially spherical, biocompatibleadsorbent material suitable for the removal of albumin-bound toxins,drugs, pharmaceuticals, endogenic and exogenic toxins from blood, bloodplasma or albumin circuits, having high adsorption speed and capacity.Furthermore there is need for a method to produce said adsorbentmaterial in a relatively simple and economical way.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a picture of the inventive absorbent particles;

FIGS. 2 a and 2 b are graphs showing the results of static and dynamicbilirubin absorption tests, respectively, using activated charcoal andthe inventive absorbent particles.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an adsorbent material consisting of ahighly cross-linked, highly porous, particulate or sphericaldivinylbenzene copolymer comprising 4 to 30 weight % of one or multiplesubstituted or unsubstituted vinylimidazole monomers, 50 to 85 weight %of divinylbenzene (DVB) and 5 to 40 weight % of ethylvinylbenzene, allincorporated into the polymer network by polymerization. Suitablevinylimidazole monomers are 1-vinylimidazole and/or 4-vinylimidazoleexclusively or in mixture. Further suitable vinylimidazole monomerscomprise 1-vinyl-2-methylimidazole, 1-vinyl-2-ethylimidazole,1-propenyl-2-methylimidazole, and 1-allyl-2-methylimidazole, exclusivelyor in various mixtures with each other or with unsubstitutedvinylimidazole monomers. The content of the imidazole monomers in theadsorbent polymer of this invention can be varied in a wide range,preferably between 5 and 20 mole %. Suitable divinylbenzene monomers arecommercially available solutions of divinylbenzene comprising 60 to 80weight % divinylbenzene isomers and 40 or 20 weight % of various isomersof ethylvinylbenzene.

The adsorbent material of this invention has an optimized specificsurface in the range from 200 to 900 m²/g and an optimized pore sizedistribution with a total pore volume from 1.0 to 2.0 cm³/g. Preferredembodiments of this invention comprise up to 0.3 cm³/g micropores, up to1.2 cm³/g mesopores and up to 0.5 cm³/g macropores. According to IUPAC(International Union of Pure and Applied Chemistry) micropores aredefined as pores with pore diameters below 20 Å, mesopores are poresbetween 20 Å and 500 Å, and macropores are pores with diameters greaterthan 500 Å. For the adsorbent material of this invention the preferredaverage pore size is in the range from 100 to 500 Å, preferably 300 Å.

Furthermore, the adsorbent material has a particle size distributionfrom 50 to 300 μm, especially if it is intended to be used in aperfusion method or in the MARS process. The particles can also beproduced in a size from 1 to 50 μm to be used in novel alternate plasma-and blood purification methods. It is a particular advantage that theparticles are predominantly spherical and that they can be produced witha narrow particle size distribution.

The adsorbent material of this invention is produced by suspensionpolymerization in the presence of selected inert substances andsuspension stabilizers. The inert substances are removed from thepolymer after polymerization. In conjunction with the DVB they areresponsible for the degree of porosity, i.e. for the pore sizedistribution and pore volume. Suitable inert substances comprisealiphatic and aromatic hydrocarbons, higher molecular alcohols, estersor suitable polymer solutions. Preferred inert substances of thisinvention comprise toluene, dichlormethane, carbon tetrachloride, butylacetate, ethyl acetate, exclusively or as a mixture. The content of theinert substance in the organic phase can be varied in the range from 25to 50 weight %.

The function of the suspension stabilizer is to prevent coagulation ofthe droplets during polymerization. Suitable suspension stabilizers ofthis invention comprise water-soluble synthetic and natural polymers,e.g. poly(vinyl alcohol), partly saponified poly(vinyl acetate), methylcellulose, hydroxyethyl cellulose, polyacrylic acid sodium salts,carboxymethyl cellulose sodium salt, and furthermore Pickeringstabilizers such as calcium phosphate, bentonite, montmorillonite,aluminium hydroxide, magnesium hydroxide, and calcium carbonate.

The suspension polymerization is initiated by a monomer soluble, radicalinitiator. Suitable initiators of this invention comprise dibenzoylperoxide, methylethylketone peroxide, and azoisobutyronitrile.Preferably, the amount of initiator is in the range of 0.2 to 2.0 weight% with respect to the monomer mixture.

In comparison with conventional activated charcoal and other commercialadsorbents the adsorbent material of this invention displays much higheradsorption capacity and adsorption speed of free and albumin-boundtoxins and poisons, particularly—as shown in the following examples—forbilirubin-albumin complexes (B-HSA solutions) and for free bile acids.

Furthermore, the adsorbent material of this invention also adsorbsN-acetyl tryptophane, octane acids, fatty acids, phenols, and caffeine,at much higher speed and capacity than other commercially availableadsorbent materials. Moreover, the adsorbent material of this inventionexhibits good biocompatibility as has been shown in cytotoxicologicaland hemolysis tests. The adsorbent material can be sterilized withoutchanging its advantageous properties and due to its good mechanicalstability it can be treated without wear debris. When applied in columnsor cartridges it shows advantageous flow behaviour so that flow rates upto 200 ml/min are possible. The adsorbent material of this invention hasbeen tested in solutions of bilirubin and human serum albumin in bothbatch tests (static bilirubin test) and under circulating conditions(dynamic bilirubin test).

The invention is further illustrated by the following examples.

EXAMPLE 1

Preparation of the Adsorbent Material (AM1)

0.28 g poly(vinyl alcohol) with a molecular weight of 49000 g/mole weredissolved in 142.5 g deionized water at 30° C. in a heated 250 mlcylindrical vessel equipped with a KPG stirrer, reflux condenser,thermometer and two baffles. 7.5 g NaCl were added and the solutionheated to 70° C. The stirring speed was set to 650 rpm. The monomersolution, comprising 18.7 g divinylbenzene, 12.5 g 1-vinylimidazole,18.7 g ethyl acetate and 0.25 g AIBN was added at once. The emulsion wasstirred for 60 min at 70° C. until a stable droplet size was establishedand then heated to 80° C. and polymerized at this temperature for 10 h.The obtained suspension was then cooled to room temperature and filteredon a suction filter. The filter cake was washed with 3 bed volumes ofdeionized water and then with 2 bed volumes of ethanol. The filter cakewas then dried for 12 at 100° C. in vacuo.

The composition of the copolymer was determined using elementalanalysis. The obtained nitrogen content was 6.2% equivalent to 20.8weight % or 26.7 mole % of vinylimidazole in thedivinylbenzene-vinylimidazole copolymer. Yield was 22 g. The obtainedparticles were spherical and they had a particle size distribution from50 to 150 μm (FIG. 1). The specific surface—determined by BET nitrogenadsorption method—was 509 m²/g. Total pore volume was 1.3 ml/gcomprising 0.25 ml/g micropores, 0.75 ml/g mesopores, and 0.3 ml/gmacropores in 1 g of the copolymer.

EXAMPLE 2

Determination of Bilirubin Adsorption

The suitability of the adsorbent material of this invention forextracorporeal blood purification was tested with a static and a dynamicbilirubin adsorption test and the results evaluated in comparison withconventionally used activated charcoal adsorbents. It is known thathuman albumin exceptionally strongly binds to bilirubin. Therefore, theadsorption behaviour of various adsorbents is observed with respect tobilirubin-human albumin complexes as a representation for numerous otheralbumin bound blood toxins and poisons.

Bilirubin is a degradation product of hemoglobin (red blood color) andis contained in bile colors. People with jaundice have an increasedlevel of bilirubin which causes the characteristic yellow color of thesepatients. Normally, bilirubin is created in the spleen by oxidativecleavage of the porphyrine ring of heme followed by hydration of thegreen intermediate product biliverdin. As a decoupling agent ofoxidative phosphorylization bilirubin is highly toxic for the organismand it is therefore bound to serum albumin in the blood circuit andtransported to the liver. In patients with acute liver failure the livercannot free the albumin from bilirubin. This function of the liver is tobe replaced by selective adsorbents in perfusion techniques and aselective membrane in the MARS process.

Structure of Bilirubin

Preparation of the Test Solution

Analogous to the environment in the human organism bilirubin wascomplexed with human serum albumin in a first step and this complexnamed B-HSA solution. To do so, 33 mg Bilirubin were weighed in areaction vessel and dissolved within 5 min in 1.25 ml 0.1 m NaOH in anultrasonic bath protected from light. After dissolution the content ofthe vessel were transferred quantitatively into a brown 100 ml flaskwhich contained 28 ml of 20% HSA solution (Aventis GmbH, Germany) and 84ml of 0.9% NaCl in water. The prepared bilirubin solution contains 5weight % albumin and 504 μmol bilirubin per liter B-HSA solution.

Conditioning the Adsorbent Materials

500 mg of dry adsorbent material were weighed into a solid phaseextraction (SPE) cartridge and placed on an SPE vacuum manifold. Theadsorbent material is rinsed consecutively with two times 5 ml 70%ethanol, five times with 5 deionized water and eventually tree timeswith 0.9% NaCl solution and then dried for 2 minutes.

Static Bilirubin Adsorption Test (Batch Method)

500 mg of the conditioned adsorbent material were placed in a vessel and5 ml B-HSA solution added. Then the vessel was shaken intensively on alaboratory shaker. In intervals of 15, 60, and 120 minutes the shakerwas stopped to draw a 100 μl sample of the overlaying solution for UVspectroscopic bilirubin determination. The sample was diluted with 0.9ml of 0.9% NaCl solution and analyzed in an 0.2 cm cuvette.

Determination of the remaining bilirubin concentration is performed atthe long wavelength absorption maximum at 453 nm. Changes of theextinction of this band correspond to changes of bilirubin concentrationin the B-HSA solution. The extinction of the B-HSA solution beforecontact with the adsorbent material was used as a reference value. Thisway, relative concentration changes can be easily determined. Theremaining bilirubin concentration was usually given as three percentvalues corresponding to the concentration after 15, 60, and 120 minutes.The reference B-HSA solution contains 5% human serum albumin and 505μmol/l bilirubin. Results are shown in FIG. 2 a.

Dynamic Bilirubin Adsorption Test (Circuit Method)

A dynamic bilirubin adsorption test was developed in order to comparethe adsorbent material of this invention with activated charcoal whichis currently typically used in medicine. This test tries to simulate theconditions present in a conventional perfusion method or in a MARSdevice. To do so, the adsorbent material is placed in solid phaseextraction cartridges (“mini cartridges”) and placed on a vacuummanifold. The adsorbent is conditioned as described above and thenloaded with B-HSA solution. When applying soft vacuum the solution flowsthrough the adsorbent material and bilirubin concentration wasdetermined in the filtrate by UV spectroscopy. The filtrate was thenreturned to the top of the cartridge and the procedure repeated 7 times.Results are shown in FIG. 2 b.

COMPARATIVE EXAMPLE

In order to compare the adsorption properties of the adsorbent materialof this invention the currently used medical activated charcoal wasconditioned in and tested in both the static and dynamic bilirubinadsorption test. FIG. 2 shows the behaviour of the activated charcoaland the adsorbent material of this invention in the static and dynamictests side by side.

The adsorption speed of the adsorbent material of this invention is muchhigher than of the currently used activated charcoal (static test, FIG.2 a). Within 1 hour Activated charcoal adsorbs ca. 60% of the bilirubinfrom the B-HSA solution. In contrast to this, the adsorbent materialadsorbs almost all (98-100%) of the bilirubin under the same conditions.

The advantage of the adsorbent material is even clearer in the dynamictest (FIG. 2 b). While activated charcoal can hardly adsorb anybilirubin under dynamic conditions the adsorbent material of thisinvention shows an exponential decrease of bilirubin concentration.After 7 cycles through the adsorbent bed the relative bilirubinconcentration in the filtrate is 25%. This result gives hope to asignificant reduction of treatment times, an increase of effectivity,and an increase of the survival rate of patients with acute liverfailure.

EXAMPLE 3

200 mg of adsorbent material AM1 were weighed into a 6 ml SPE cartridgeand conditioned with 5 ml of 70 weight % ethanol, 5 ml distilled waterand 5 ml 0.9% NaCl solution. The conditioned adsorbent material was thenloaded with 2 ml of a bile acids solution (c=1 mg/ml) in 0.9% NaClsolution. 20 μl of the eluate were then injected on a GPC column (HEMA2000, PSS Standards Service GmbH, Mainz, Germany), eluted with 0.9% NaClsolution and detected with an RI detector. Loading with bile acidssolution was repeated until the chromatogram showed a signal for bileacids. From the number of load steps until this event the capacity ofadsorbent material could be determined to be 210 mg bile acids per gramadsorbent material AM1.

1. An adsorbent material, based on crosslinked, porousimidazole-divinylbenzene copolymers, for application in blood-, bloodplasma-, and albumin purification processes, said adsorbent materialbeing formed by radical suspension polymerization of a monomer mixtureof divinylbenzene crosslinker and an imidazole derivative, wherein thepolymerization is conducted in the presence of air and/or oxygen, asalt, a stabilizer, and an inert substance; the adsorbent materialcontains 5 weight % to 30 weight % of the imidazole derivative; theadsorbent material has a specific surface from 200 m²/g to 900 m²/g anda total pore volume from 1.0 cm³/g to 2.0 cm³/g where 1 g of thematerial contains up to 0.3 cm³ micropores, up to 1.2 cm³ mesopores, andup to 0.5 cm³ macropores; and the adsorbent material is essentially ofspherical shape having a particle size range from 1 μm to 300 μm and anaverage pore diameter in the range of 100 Å to 500 Å.
 2. The adsorbentmaterial of claim 1 where the divinylbenzene copolymer comprises 50weight % to 85 weight % of isomeric divinylbenzene and 5 weight % to 40weight % of isomeric ethylvinylbenzene.
 3. The adsorbent of claim 1comprising predominantly spherical particles having a particle size from50 μm to 200 μm.
 4. The adsorbent material of claim 1 where theradically polymerizable imidazole derivative are 1-vinylimidazole,4-vinylimidazole, 1-vinyl-2-methylimidazole, 1-vinyl-2-ethylimidazole,1-propenyl-2-imidazole, 1-allyl-2-methylimidazole, exclusively ormixtures thereof, or an unsubstituted imidazole monomer.
 5. Theadsorbent of claim 1 comprising predominantly spherical particles havinga particle size from 1 μm to 50 μm.
 6. A method of suspensionpolymerization to produce the adsorbent material of claim 1 where theaqueous phase comprises 5 weight % to 25 weight % of a salt and 0.5weight % to 5 weight % of a suspension stabilizer, the organic phasecomprises 25 weight % to 50 weight % of an inert substance, and thepolymerization is conducted in the presence of air and/or oxygen.
 7. Themethod of claim 6 where the inert substance comprises toluene, ethylacetate, butyl acetate, dichlorethane, or carbon tetrachioride,exclusively.
 8. The method of claim 6 where the suspension stabilizercomprises poly(vinyl alcohol) or methyl cellulose or hydroxyethylcellulose or calcium phosphate or aluminium hydroxide or magnesiumhydroxide.
 9. The method of claim 6 where the inert substance comprisesa mixture of at least two inert substances selected from the groupconsisting of toluene, ethyl acetate, butyl acetate, dichlorethane, andcarbon tetrachloride.
 10. A method of blood purification in plasma- orblood purification processes comprising: (a) providing an adsorbentmaterial based on crosslinked, porous imidazole-divinylbenzenecopolymers, said adsorbent material being formed by specific radicalsuspension polymerization of a monomer mixture in the presence of airand/or oxygen, a salt, and an inert substance, said adsorbent materialcomprising at least 50 weight percent divinylbenzene crosslinker and 4to 30 weight percent of an imidazole derivative, said adsorbent materialbeing highly crosslinked and highly porous, said adsorbent materialhaving a spherical shape and specific characteristics of surface, poresize distribution, pore diameter, and particle size range, forapplication in blood-, blood plasma-, and albumin purificationprocesses, where said adsorbent material has an average pore diameter inthe range of 100 Å to 500 Å and 1 g of the material contains up to 0.3cm³ micropores, up to 1.2 cm³ mesopores, and up to 0.5 cm³ macropores;and (b) applying the adsorbent material to blood or blood plasma.
 11. Amethod of blood purification comprising: (a) providing an adsorbentmaterial based on crosslinked, porous imidazole-divinylbenzenecopolymers, said adsorbent material being formed by specific radicalsuspension polymerization of a monomer mixture in the presence of airand/or oxygen, a salt, and an inert substance, said adsorbent materialcomprising at least 50 weight percent divinylbenzene crosslinker and 4to 30 weight percent of an imidazole derivative, said adsorbent materialbeing highly crosslinked and highly porous, said adsorbent materialhaving a spherical shape and specific characteristics of surface, poresize distribution, pore diameter, and particle size range, forapplication in blood-, blood plasma-, and albumin purificationprocesses, where said adsorbent material has an average pore diameter inthe range of 100 Å to 500 Å and 1 g of the material contains up to 0.3cm³ micropores, up to 1.2 cm³ mesopores, and up to 0.5 cm³ macropores;and (b) applying the adsorbent material to blood in a MolecularAdsorbent Recirculating System (MARS).
 12. A method of bloodpurification comprising: (a) providing an adsorbent material based oncrosslinked, porous imidazole-divinylbenzene copolymers, said adsorbentmaterial being formed by specific radical suspension polymerization of amonomer mixture in the presence of air and/or oxygen, a salt, and aninert substance, said adsorbent material comprising at least 50 weightpercent divinylbenzene crosslinker and 4 to 30 weight percent of animidazole derivative, said adsorbent material being highly crosslinkedand highly porous, said adsorbent material having a spherical shape andspecific characteristics of surface, pore size distribution, porediameter, and particle size range, for application in blood-, bloodplasma-, and albumin purification processes, where said adsorbentmaterial has an average pore diameter in the range of 100 Å to 500 Å and1 g of the material contains up to 0.3 cm³ micropores, up to 1.2 cm³mesopores, and up to 0.5 cm³ macropores; and (b) applying the adsorbentmaterial to blood as a sorbent for bilirubin and bile acids.